Within the field of vapor deposited thin film production, it is well known that film properties depend upon film microstructure. For certain applications, film structures comprising layers of differing composition which repeat in a periodic fashion have desirable properties; such structures will be referred to herein as "multilayered structures" or "multilayers".
Optical coatings consisting of periodically alternating layers of high refractive index and low refractive index dielectric materials are examples of technically useful multilayered structures in which optical properties can be tuned to a particular application by appropriately selecting certain features, for example, the number of layer periods and layer thickness. Magnetic or magneto-optical recording materials are further examples of materials in which a multilayered structure can be utilized to alter or optimize thin film properties. For example, deposition of alternating thin (typically .ltoreq.1 nanometer) layers of Fe and Tb can be used to produce a magneto-optical recording material; a Fe-Tb film of, e.g. 50 nm thickness would thus typically consist of 25 or more Fe-Tb layer pairs. By varying the Fe and Tb layer thickness, magnetic properties such as coercivity and anisotropy can be controlled.
Multilayer deposition methods described in the prior art employ some mechanical means to expose substrates to two or more deposition source fluxes in a repetitive, sequential manner, and the deposition sources are typically operated continuously. Apparatus based on the above methods are used for multilayer deposition on discrete, non-continuous substrates.